Process for biomass conversion to synthesis gas

ABSTRACT

Biomass is processed through a biomass fractioning system that creates, through the application of selective temperature ramps and pressure shocks, a series of useful volatile components and BMF char, wherein the BMF char is reacted sacrificially with any one stream of methane, carbon dioxide, steam or oxygen to create highly pure synthesis gas with a controllable range of compositions. The resulting synthesis gas may be used in any desired manner, including conversion to oxygenates such as methanol and dimethyl ether, and to hydrocarbons.

TECHNICAL FIELD

The present invention relates generally to systems for making renewablefuels, and snore particularly to the conversion of char generated usinga reactor to produce highly pure synthesis gas that can ultimatelygenerate value added chemicals and renewable fuels.

DESCRIPTION OF THE RELATED ART

The planet is warming and solutions are being sought to decrease themagnitude of this effect. Global temperatures are expected to increaseby at least 2 degrees Celsius by the middle of the century. The rise ofglobal temperatures is expected to produce significant disruptions tothe global ecosystem and to the lives of millions of individuals acrossthe planet. Processes that reduce carbon emissions in a significantmanner are urgently needed. The Fischer-Tropsch process converts amixture of carbon monoxide and hydrogen (synthesis gas) intohydrocarbons of varying numbers of carbon, which can then be upgraded todiesel, gasoline, aviation fuel, lubricants and chemicals. AFischer-Tropsch process that utilizes renewable sources as feedstock ishighly desired to achieve global carbon emissions reductions. Synthesisgas can also be converted in another processing route to emerging fuelsmethanol and dimethyl ether (DME), which can be converted to gasoline.As long as the synthesis gas that is used in the process is derived froma renewable resource, this process may have an important effect incontrolling carbon emissions.

Present Fischer-Tropsch or methanol processes rely on differentfeedstock of varying degrees of quality, that is mostly derived fromeither the steam reforming of natural gas or from the gasification ofcoal. Fischer-Tropsch projects generally consist of synthesis gasgeneration, Fischer-Tropsch synthesis and product upgrading. A problemwith these approaches is that the synthesis gas produced from coal andthe natural gas feedstock for steam reforming has high impurities(particularly sulfur-containing compounds), or requires complicated andexpensive equipment to clean impurities in the produced synthesis gas.These impurities derive from the source methane or the source coal. Highpurity synthesis gas is desired due to the extreme sensitivity ofFisher-Tropsch catalysts to impurities such as sulfur and chloride.

Present Fischer-Tropsch or methanol processes rely on synthesis gas witha desired hydrogen to carbon monoxide (H₂/CO) ratio. The preferred H₂/COratio for the Fischer-Tropsch process is about 2. Synthesis gas obtaineddirectly from steam methane reforming has an excess of hydrogen.Synthesis gas obtained directly from coal gasification is deficient inhydrogen. Therefore, the H₂/CO ratio must be adjusted using complicatedand expensive equipment. The present approach allows adjustment of theratio of hydrogen to carbon monoxide by varying the source and quantityof reactants.

Various forms of laboratory and small scale commercial biomasspyrolyzers have been developed to generate useful chemical products fromthe controlled pyrolysis of biomaterials ranging from wood chips tosewage sludge. Although some pyrolyzers are focused simply on producingsynthesis gas, there is considerable effort in the development of milderpyrolyzing conditions, which typically results in a condensed liquidcommonly known as bio-oil or pyrolysis oil. Many forms of pyrolyzershave been developed at the laboratory level to produce theseintermediate compounds, which are collectively referred to as bio-oil orpyrolysis oil. Configurations include simple tube furnaces where thebiomass is roasted in ceramic boats, ablative pyrolyzers where wood isrubbed against a hot surface, various forms of fluidized bed pyrolyzerswhere biomass is mixed with hot sand, and various simpler configurationsthat are based on earlier coking oven designs.

The fundamental problem with the resultant pyrolysis oil is that it ismade up of hundreds to thousands of compounds, which are the result ofsubjecting the raw biomass to a wide range of temperature, time, andpressure profiles in bulk. When this process is complicated by thethousands of major bio-compounds in the original bio-feedstock, theresult is a nearly intractable array of resultant compounds all mixedtogether. Char (also referred to as bio-char) is also produced in themix. Pyrolysis oils from such processes are typically notthermodynamically stable. They contain active oxygenated free radicalsthat are catalyzed by organic acids and bases such that these oilstypically evolve over a period of a few days from light colored liquidsto dark mixtures with tar and resinous substances entrained in the mix.Also, attempts to re-gasify pyrolysis oil typically result in additionalchemical reactions, which produce additional biochar and a shift tolower molecular weight components in the resulting gas stream Althoughfairly high yields of pyrolysis oil can be achieved in laboratory scaleexperiments, larger industrial scale demonstration projects typicallyproduce much lower yield. This is presumably due to the wider range oftemperatures, hold times, and localized pressures within the much largerheated three dimensional volumes of such scale-up architectures. Thusthe pyrolysis oil is not stable enough nor the biochar is pure enoughfor further processing without needing complicated and expensiveequipment to remove impurities in the synthesis gas.

The production and reactions of charcoal have been known since the startof the industrial revolution. The following discussion is limited tosynthesis gas production from biomass. There exist several approaches tothe production of synthesis gas from biomass. U.S. Pat. No. 6,133,328discloses a method whereby biomass is decomposed with stored hot air toincandescent carbon at 1000° C. The hot air is cutoff and steam isintroduced to react with the carbon to produce hydrogen and carbonmonoxide. Additional steam is introduced to react with the exitingcarbon monoxide to carbon dioxide and additional hydrogen, therebybringing the ratio of H₂/CO to 2.0. U.S. Pat. No. 4,497,637 disclosesthe conversion of biomass to synthesis gas via a system that pyrolyzesbiomass with pyrolysis oil and preheated air. Char, pyrolysis oil andpyrolysis gas are generated. Pyrolysis gas is diverted to dry theincoming biomass, while the char and pyrolysis oil are gasified withsteam and oxygen to produce synthesis gas.

U.S. Pat. No. 7,226,566 teaches a method of producing fuel and charcoalfrom biomass that entails an apparatus comprised of a multistagereaction chamber, a biomass delivery system, a charcoal removal system,a fuel gas removal system, filter, pump, demister, heat exchanger, andfuel storage. The upper level of the reaction chamber embodies thebiomass input, the middle layer includes a pyrolysis region generatingsynthesis gas and water vapor, and the lower level comprises a charcoalbed. The system is said to be a one-container system for the productionof fuel from biomass. Similar concepts are expressed in U.S. Pat. Nos.4,268,275, 4,421,524 and 4,530,702.

U.S. Pat. No. 6,747,067 by Melnichuk et al teaches a method ofgenerating synthesis gas from biomass in which cellulosic feedstock iscontinuously fed into a heated vessel between 675° C. and 900° C. in theabsence of oxygen. The heated vessel receives a continuous infusion ofsteam which cracks said cellulose feedstock into fly ash, carbon, carbonmonoxide and hydrogen. The carbon particulates are mechanically removedand reacted with steam at 400-500° C. and 3-15 atmospheres to cause awater gas shift. Korean Patent 100819505 teaches a unified system forsteam reforming tar and soots to synthesis gas that uses large diameterbiomass gasifiers.

U.S. Patent Application Nos. 2010/0270505 and 2009/0151251 disclosepyrolyzing a carbon containing feedstock to form a pyrolyzed feed streamsuch as char, which is then converted to synthesis gas, typically via awater shift reaction. U.S. Patent Application No. 2009/0183430 teaches asystem for the production of synthesis gas from biomass utilizing ameans for compacting the biomass, removing air from said biomass duringthe compaction, and heating the biomass at sufficiently hightemperatures (greater than 950° C.) to create synthesis gas and ash. Nochar is said to be formed.

Synthesis gas is typically obtained from steam reforming of methane.Methane reformation requires apparatus for feedstock purification toreduce sulfur and chloride levels which easily poison the catalyst.After reformation, in order to obtain product components of high purity,separation or additional processes are often instituted after thesecomponents have been formed. There is usually a step to separate thehydrogen from CO and CO₂. There is yet another step to separate CO fromCO₂. Thus U.S. Pat. No. 4,861,351 discloses a hydrogen product of 98+%purity after having selectively adsorbed CO and CO₂ with differentsorbents. Other methods rely on cryogenic separation of CO₂. U.S. Pat.No. 7,846,979 discloses the use of a biomass feedstock to generatesynthesis gas and CO₂. The CO₂ is recycled by reacting with ahydrogen-rich mixture obtained from steam reformation to produce CO andH₂O. In this manner synthesis gas with a ratio of H₂/CO of 2.15 isobtained.

BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION

The above-described methods of generating synthesis gas from bio-chardiffer substantially from the methods of the invention, which utilize anovel type of char referred as biomass fractionated (BMF) char. The BMFchar may be generated according principles disclosed in co-filed U.S.patent application Ser. No. 13/103,905 entitled “Method for BiomassFractioning by Enhancing Thermal Conductivity.” BMF char is generated ina unique manner using a biomass fractioning reactor in which biomass isfractioned into thin sheets, and the thin sheets are subject to specifictemperature ramps and pressure shocks.

According to various embodiments of the invention, the adjustment ofsynthesis gas ratio is unique in that it is controlled by the nature andquantity of the feedstock. Depending on whether the feedstock ishydrogen-rich or oxygen-rich, a wide spectrum of synthesis gascompositions may be obtained.

Another embodiment features a method for producing synthesis gas frombiomass, comprising: grinding a biomass feedstock to produce groundbiomass particles; dispensing the ground biomass particles into thinsheets; subjecting the thin sheets of ground biomass to a treatmentincluding sequential or concurrent ramps of temperature and pressureshocks; and recovering a residual non-volatile biomass component fromthe treatment and reacting the component with at least one of methane,oxygen, steam, and carbon dioxide, at high temperatures.

An additional embodiment involves a method for adjusting the ratio ofhydrogen to carbon monoxide in synthesis gas, comprising: grinding abiomass feedstock to produce ground biomass particles having diametersin the range of 0.001 inch to 1 inch; dispensing ground biomass intothin sheets having a thickness that is a multiple of the ground biomassparticle diameter; subjecting the ground biomass to sequential orconcurrent ramps of temperature and pressure shocks; selectivelycollecting various groups of volatile compounds as they are releasedfrom the biomass; collecting a remaining non-volatile component of thethin sheets; reacting the non-volatile component with one of oxygen,methane, steam, and carbon dioxide; and adjusting a ratio of reactedoxygen, methane, steam, or carbon dioxide to produce synthesis gashaving a hydrogen/carbon ratio in a range of 0 to 100.

Embodiments of the invention use a novel type of char created from abiomass fractionator (i.e., BMF char) for the production of high puritysynthesis gas.

Further embodiments of the invention use BMF char to create a synthesisgas mixture with a wide composition of hydrogen and carbon monoxide

Additional embodiments of the invention are directed toward methods thatreact vast stores of methane with BMF char to ultimately generate valueadded chemicals.

Yet further embodiments of this invention are directed toward methods tosynthesize gasoline using reactions on BMF char.

Other features and aspects of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, which illustrate, by way of example the featuresin accordance with embodiments of the invention. The summary is notintended to limit the scope of the invention, which is defined solely bythe claims attached hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention, in accordance with one or more variousembodiments, is described in detail with reference to the followingfigures. The drawings are provided for purposes of illustration only andmerely depict typical or example embodiments of the invention. Thesedrawings are provided to facilitate the reader's understanding of theinvention and shall not be considered limiting of the breadth, scope, orapplicability of the invention. It should be noted that for clarity andease of illustration these drawings are not necessarily made to scale.

FIG. 1 is a flow diagram showing biomass conversion to BMF char withsubsequent reaction in a BMF char reactor.

FIG. 2 illustrates an alternate method of loading biomass onto arotating disc supporting biomass reaction chambers.

FIG. 3 is a diagram illustrating a process for generating the BMF char.

FIG. 4 illustrates an embodiment of applied pressure and temperature andcorresponding biomass response.

FIG. 5 illustrates an embodiment in which a BMF char reaction chamber islocated within a rotating disc.

FIG. 6 is a scanning electron microscope (SEM) image of BMF char fromcorn after its formation.

FIGS. 7 a and 7 b show XRF data of BMF char from red fir and corn cob,respectively.

FIGS. 8 a-8 d show mass spectrometry data for reaction products of BMFchar with different reactants.

The figures are not intended to be exhaustive or to limit the inventionto the precise form disclosed. It should be understood that theinvention can be practiced with modification and alteration, and thatthe invention be limited only by the claims and the equivalents thereof.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

The present invention is directed toward biomass fractioning, wherebybiomass is processed through a biomass fractioning system that creates aseries of useful volatile components and BMF char through theapplication of selective temperature ramps and pressure shocks. Inparticular, the BMF char is reacted with any one stream of methane,carbon dioxide, steam or oxygen to create highly pure synthesis gas witha controllable range of compositions. The resulting synthesis gas may beused in any desired manner, including conversion to oxygenates such asmethanol and dimethyl ether, and to Fischer-Tropsch products such asgasoline, diesel, lubricants and naptha.

Unlike conventional methods that produce synthesis gas having highimpurities, embodiments of the invention produce high purity synthesisgas via conversion of BMF char. Additionally, some embodiments allow forthe adjustment of the ratio of hydrogen to carbon monoxide by varyingthe source and quantity of reactants. Further embodiments of theinvention employ a novel char that is sufficiently clean to be processedfurther for high purity synthesis gas production.

BMF Char Generation

Embodiments of the present invention involve synthesis gas productionfrom BMF char. Specifically, this char may be generated following theprinciples disclosed in co-owned, co-pending U.S. patent applicationSer. No. 13,103,905 entitled “Method for Biomass Fractioning byEnhancing Thermal Conductivity,” the content of which is incorporatedherein by reference in its entirety. The following discussionillustrates the BMF char generation. Referring now to FIG. 1, biomass 50is loaded piecemeal onto a plurality of movable biomass reactionchambers 51. By way of example, the compartments may be made movableusing conventional drive mechanisms such as gear drives, chain drives,ratcheting sprockets, etc. In addition to linear displacements, thereaction chambers 51 may also be arranged on a disc that rotatescontinuously or in a stepwise fashion as shown in FIG. 2. The biomass 50is then passed to a biomass fractioning reactor 60 that allows theproduction of high-yield bio-intermediary compounds 61 and residual char52 (i.e., BMF char).

As used herein, the term ‘biomass’ includes any material derived orreadily obtained from plant sources. Such material can include withoutlimitation: (i) plant products such as bark, leaves, tree branches, treestumps, hardwood chips, softwood chips, grape pumice, sugarcane bagasse,switchgrass; and (ii) pellet material such as grass, wood and haypellets, crop products such as corn, wheat and kenaf. This term may alsoinclude seeds such as vegetable seeds, sunflower seeds, fruit seeds, andlegume seeds.

The term ‘biomass’ can also include: (i) waste products including animalmanure such as poultry derived waste; (ii) commercial or recycledmaterial including plastic, paper, paper pulp, cardboard, sawdust,timber residue, wood shavings and cloth; (iii) municipal waste includingsewage waste; (iv) agricultural waste such as coconut shells, pecanshells, almond shells, coffee grounds; and (v) agricultural feedproducts such as rice straw, wheat straw, rice hulls, corn straw, cornstraw, and corn cobs.

With further reference to FIG. 1, the biomass may be ground by a varietyof techniques into a particle size suitable for dispensation into thereaction chamber 51. Particle size may range from 0.001 inch to 1 inchin diameter, limited by processing equipment size and thermal transferrates.

Embodiments of the invention feature a biomass chamber 51 that is muchwider and longer than it is thick. In some cases, biomass is dispensedinto thin sheets whose total thickness is 1 to 30 times the biomassparticle size. A preferred thickness for the chamber for uncompressedbiomass (which is ground or chopped to ⅛″ or smaller) is approximately¾″ in thickness. As the biomass is heated and further pulverized (asdiscussed below), the emerging BMF char quickly condenses to a layerabout 1/10″ thick. This aspect ratio ensures mild pyrolyzing conditionsthat allow the collection of useful chemical compounds known asbio-intermediary compounds as well as the production of BMF char. Aperson of skill in the art will appreciate that these biomass chamberscan be sized in width and length along with the diameter of theircorresponding drive disc to any such size as appropriate for the desiredthroughput for the biomass fractionator, without departing from thescope if the invention.

Referring to FIG. 3, the ground biomass is passed to biomass fractioningreactor 60, which subjects the biomass to a series of temperature rampprofiles (ΔTn) and pressure shock profiles (ΔPn), where n is an integergreater than 1 that describes the stages in the step-wise decompositionof the biomass. In particular, the biomass is subjected first to aheating profile ΔT1, typically a linear temperature ramp, by a heatingagent such as a metal anvil at processing station 58. Typically, thepurpose of this first ΔT1 profile is to dewater the biomass. SubsequentΔTn profiles end at progressively higher temperatures and serve thepurpose of outgassing and of thereto-chemically converting solid biomassto volatile bio-compounds. These useful bio-compounds with progressivelyhigher devolatilization temperatures. In order to accomplish thisdevolatilization in a selective manner, the temperature treatment isaccompanied by a pressure treatment. In the illustrated embodiment, thisis achieved using compacting station 59 (e.g., a series of anvils) forsubjecting the biomass to accompanying pressure profiles ΔPn comprisinga sequence of pressure shocks that exploit the inherent compressionalfeatures of carbon.

In some embodiments, the temperature profiles are linear ramps rangingfrom 0.001° C./sec to 1000° C./sec, and preferably from 1° C./sec to100° C./sec. Processing heating station 58 may be heated by electricalheating elements, direct flame combustion, or by directed jets of heatedworking gas or supercritical fluid. The heating profile and the pressurecompaction profile may be linked via a feedback loop and may be appliedby the same agent simultaneously. Compacting station 59 may becontrolled by electrically driven devices, air compressed devices, orany other form of energy that serves to impact load the biomass. BMFchar 52 remains after these processing steps.

The selective pyrolysis of the biomass arises out of the interplaybetween the applied pressure pulses, applied temperature and resultantpressures and temperatures experienced by the biomass. The process isillustrated diagrammatically in FIG. 4, which shows applied pressure,biomass temperature, biomass pressure and anvil position as a functionof time. It is understood that a wide variety of different types ofpressure pulses may be applied, and that the entire illustration is apedagogic device. In FIG. 4, pressure shocks applied via compactingstation 59 are shown as a series of triangular pressure pulses with anunspecified rest time. The process starts out by utilizing the thermalconductivity of water. The biomass is first subjected to a temperatureramp sufficient to cause the biomass to release water. The releasedheated water vapor is then subjected to a pressure shock whichcompresses the steam, thus accelerating the biomass decomposition. Itmay be possible for the steam to attain supercritical form, though thatis not a requirement for the present invention.

With continued reference to FIG. 4, the pressure shock also aids incollapsing the biomass. A short time after peak pressure is applied, theanvil is pushed back by the pressure of extracted volatile compounds.When the volatile compounds are removed along with the steam, pressurewithin the biomass is decreased suddenly. Biomass temperature rapidlyreturns to base levels, and the anvil returns to its unextended baseposition. After the water has been removed entirely from the biomass,the applied temperature causes hot localized areas within the biomassthat initiate carbon formation. Compressive impacts on the newly formedcarbon serve in turn to increase the theimal conductivity of the carbon.The increased thermal conductivity serves to efficiently transmit heatenergy needed to break down the biomass to the next stage in itsdecomposition. Furthermore, because carbon exhibits compressionalmemory, compressive impacts are sufficient to exert this effect onthermal conductivity.

The compressional memory of carbon has been indirectly demonstrated instudies of commercial carbon resistors as low pressure gauges. SeeRosenberg, Z. et at International Journal of Impact Engineering 34(2007) 732-742. In these studies, metal discs were launched from a gasgun at high velocity and impact an epoxy or Plexiglas target in which acarbon resistor is embedded. Resistance changes were measured as afunction of time after impact. It was noted that the resistancedecreased rather rapidly in less than a microsecond, and stayed low forseveral microseconds, in some cases over 10 microseconds, until it beganto increase gradually to pre-impact levels. There is essentially amemory effect or a slow relaxation after the impact. As electricalresistance and thermal conductivity are inversely correlated for carbonas for metals (See, for example, Buerschaper, R. A. in Journal ofApplied Physics 15 (1944) 452-454 and Encyclopedia of ChemicalTechnology, 5th edition), these studies reveal a compression memory onthe part of the carbon. This compression memory is at least partlyutilized in embodiments of the invention.

Embodiments of the invention also utilize the increase in thermalconductivity as carbon is compressed. The change in electricalresistance with pressure in carbon microphones is a well-known effectutilized by carbon telephones and carbon amplifiers. U.S. Pat. No.203,016, U.S. Pat. No. 222,390 and U.S. Pat. No. 474,230 to ThomasEdison, describe apparatus that transform sound compressions(vibrations) to changes in electrical resistance of carbon granules.Carbon is even more sensitive than most metals in its inverserelationship between electrical resistance and thermal conductivity.Below are data indicating the thermal conductivity of various substances(CRC Handbook of Chemistry and Physics, 87th edition) in comparison tothe measured thermal conductivity of BMF char:

TABLE 1 Select Thermal Conductivities in W/(m · K) Copper 390 StainlessSteel 20 Water 0.6 Dry Wood 0.3 Fuels 0.1 to 0.2 Carrier Gases (H₂, N₂,etc.) 0.01 to 0.02 Carbon Char 0.01 to 0.05 BMF char 1 to 5

As the thermal conductivity of the formed carbon within the biomassincreases due to pressure shocks, it becomes consequently easier toattain mild pyrolysis conditions within the biomass. As highertemperatures are reached, the fact that carbon is a better heat transferagent than water enables higher boiling compounds to become volatile.Pressure shocks serve to compress these higher boiling compounds andcontribute to fracturing cell walls within the biomass. The process isillustrated by FIG. 4 which shows anvil extension at peak pressuregetting longer with subsequent pulse application, thus indicatingsuccessive biomass pulverization in conjunction with release of usefulhigher boiling compounds.

A variety of pressure profiles ΔPn are effective in increasing thecarbon thermal conductivity. The magnitude of the pressure can vary from0.2 MPa to 10 GPa and may be applied via a number of differenttechnologies, including air driven pistons, hydraulically drivenpistons, and explosive driven devices. The duration of the pressureapplication can vary from 1 microsecond to 1 week. It is understood thatpressure pulses of different magnitudes and different time durations maybe admixed to yield optimum results.

The efficient heat energy transfer executed by embodiments of thepresent invention can be enhanced by the addition of supercriticalfluids in the reaction chamber. It is known that supercritical fluidscan improve heat transfer as well as accelerate reaction rates. Certainembodiments can operate with supercritical carbon dioxide, supercriticalwater, supercritical methane, supercritical methanol, or mixtures of theabove. It is possible that supercritical conditions are createdinternally with some pressure and temperature profiles.

A system capable of embodying the methods of the present invention isdescribed in co-owned, co-pending U.S. Patent Application No.2010/0180805 entitled “System and Method for Biomass Fractioning,” thecontent of which is incorporated herein by reference in its entirety.This system comprises a biomass load and dump station, a heatedpulverizing processing station for compressing the biomass, a biochardumping station for removing residual biochar, and a plurality ofbiomass reaction compartments able to carry the biomass from station tostation.

After the BMF char is formed, it may be reacted in situ as shown in FIG.5, or it may be optionally transferred as shown in FIG. 1 to asubsequent activation chamber 53 prior to being dispensed into a BMFchar reactor 54. The transfer may be accomplished via any number ofconventional mechanical means such as a press bar outfitted with ascraping knife. BMF char formed from this process is different thancarbonaceous deposits formed from pyrolyzers or coke from petroleumplants, since it exhibits greater thermal conductivity while maintaininghigh surface area. A scanning electron microscope (SEM) image of BMFchar after formation is shown in FIG. 6.

BMF Char Activation

The BMF char is preferably activated prior to use. Activation is awell-known procedure for increasing char surface area and adsorptivecapabilities. See, for example, discussion by Lima, I. M. et al, inJournal of Chemical Technology and Biotechnology, vol. 85, (2010), pp.1515-1521. The activation step is an optional pretreatment and selectivecombustion step which aims to create additional surface area toaccelerate subsequent desired reactions. Typical activating agentsinclude CO₂, H₂O and O₂. Table 2 shows data acquired using differentactivation agents at 900° C. for BMF char generated using a biomassfractioning reactor. In the case, the BMF char was derived from corncobs.

The increased surface area of the BMF char upon activation comes at theexpense of loss of material, which serves to create a porous structurewithin the char. Whether exposed to oxygen or methane and air, a loss ofapproximately 40% of the initial weight was measured. Activationprocedures can produce surface areas in excess of 500 m²/g.

TABLE 2 Effect of Activating Agent on BMF Char Activation BMF ActivatedChar Activation Activation Temp Char BMF Source Agent Time ° C. Loaded,g Char, g Corn Cobs O₂ 3 Hours 900 47.5 29 Corn Cobs CH₄ , air 3 Hours900 46     29.5

BMF Char Reactions

BMF char can be reacted in char reactor 54 with one of CH₄, H₂O, CO₂ andO₂ as illustrated by the reactions:C+CH₄->2H₂+2C ΔH°=75 kJ/mol  [1]C+H₂O->CO+H₂ ΔH°=132 kJ/mol  [2]C+CO₂->2CO ΔH°=172 kJ/mol  [3]C+½O₂->CO ΔH°=−110 kJ/mol  [4]

Equation 1 may be more appropriately written as:C_(BMF)+CH₄->2H₂+C_(BMF)+C_(methane)  [1a]

Thus the carbon in equations 2, 3, and 4 may represent either BMF carbonor carbon from methane, or both.

Any one of the above gaseous reactants with the BMF char may beintroduced in supercritical form for faster kinetics. The oxygenconcentration should be controlled to avoid complete oxidation of thechar as:C+O₂->CO₂ ΔH°=−393 kJ/mol  [5]

The first three reactions are endothermic, while the fourth isexothermic. The energy for the first three reactions can come fromchanneling internal heat generated from the fourth reaction or fromexternal sources, e.g., combustion of coal or natural gas, orelectricity during off-peak hours. In principle, the heat generated fromcreating 2 moles of CO via the fourth reaction can be used to power thefirst three reactions. The following reactions are also relevant forthis discussion:H₂O+CO->H₂CO₂ ΔH°=−41 kJ/mol  [6]CH₄+³/2O₂->CO2+2H₂O ΔH°=−802 kJ/mol  [7]CH₄+¼O₂->CO+2H₂ ΔH°=−35 kJ/mol  [8]CH₄+H₂O->CO+3H₂ ΔH°=207 kJ/mol  [9]

Equation 1 in particular deserves notice for allowing vast stores ofmethane to be converted to hydrogen. Present methane reformation on coalproduces synthesis gas contaminated with sulfur, since the coaltypically contains a few percent by weight of sulfur. The sulfur in thesynthesis gas causes catalyst poisoning, and it is removed from thesynthesis gas before introducing the latter into a catalyst bed. Thisrepresents extra cost and complexity, particularly for small scalemodular plants. According to embodiments of the invention, the BMF charis actually cleaner than the incoming methane, leading to high puritysynthesis gas.

FIGS. 7 a and 7 b demonstrate an X-ray fluorescence spectra of BMF charfrom 2 different sources, specifically red fir and corn cobs. The datademonstrates a scan up to 15 keV. If sulfur were present in significantamounts, it would be evident at around 2.2 keV. It is clear for bothsources that although the mineral distribution varies between the two,sulfur is not present above background levels. Most of the peaks above 8keV are background chamber peaks and are not labeled.

Equation 1a evinces that carbon atoms from methane decomposition add afresh layer to the BMF char surface. Any impurities in the methanefeedstock, such as sulfur-based impurities, will tend to be buried inunderlying high surface area char surface and eventually accumulate inthe ash. The methane may be derived from a number of sources, includingstranded gas and wet gas. This process is thus inherently resistant toimpurities, but still able to produce high purity synthesis gas. Theability to add oxygen or water ensures that the BMF char surface remainsactive, as long as the CO removal rate is greater than the carbondeposition rate from the methane reaction. The BMF char can thus beconsidered to act as a sacrificial catalyst in that it is not consumedin the overall reaction, but does react sacrificially duringintermediate stages.

The oxygen in the above reactions may economically be obtained from anair stream. It may also be obtained from a gas that comprises oxygenwith a different concentration, such as gas containing pure oxygen, orgas obtained from the decomposition of an oxygen carrying species suchas N₂O, H₂O, H₂O₂ or alcohols.

FIG. 8 a shows a background mass spectrum of a helium gas stream afterit has been exposed to BMF char of the present invention at 900° C. Itis shown that background levels of hydrogen (mass 2) are around 6×10⁻⁷Torr and the background levels of carbon monoxide/nitrogen are 1×10⁻⁷.Some outgassing is evident in the detectable background level of carbondioxide (mass 44) at 2×10⁻⁷ Torr. FIG. 8 b demonstrates results afteroxygen in a helium carrier is passed through the BMF char at the sametemperature. The mass spectrum of the exit gas demonstrates a majorproduction of CO along with a minor component of carbon dioxide. FIG. 8c shows the results after steam in a helium carrier is reacted with theBMF char at the same temperature. As expected, synthesis gas isproduced, as demonstrated in several orders of magnitude increase inhydrogen and carbon monoxide levels above background.

Any one combination of CH₄, H₂O, CO₂ and O₂ may be also be used to reactwith the BMF char to create synthesis gas reaction products, includingoxygenates such as aldehydes, ethers, esters, alcohols, andcarboxylates. The following lists the possible combinations in relationto reactions involving BMF char and a methane stream:C+CH₄O₂C+CH₄+H₂OC+CH₄+CO₂C+CH₄+H₂O+O₂C+CH₄+CO₂+O₂C+CH₄+H₂O+CO₂C+CH₄+O₂+H₂O+CO₂

In these cases, proper channeling of reactants is required to minimizeformation of carbon dioxide as given in equations 6 and 7. FIG. 8 ddemonstrates the results after a mixture of methane and water in ahelium carrier is reacted with the BMF char at 900° C. Increased levelsof synthesis gas were observed as compared with water alone.

The preferred temperature range for the BMF char reactions listed aboveis in the range of 800° C. to 1100° C., and most preferably 850° C. to1050° C. The synthesis gas produced is used in process 55 for a widevariety of purposes. It may be converted into oxygenates andhydrocarbons via a number of different catalytic processes, includingmethanol synthesis processes, Fischer-Tropsch chemistry, and synthesisgas fermentation. The synthesis gas may also be directly combusted. Thehydrogen may be separated from the carbon monoxide and used as feedstockfor the ammonia synthesis process or as a reactant in fuel cells. TheBMF char may also be combined at any stage after its formation withtypical chars.

Adjustment of H2/CO Ratio in BMF Char Reactions

The reactions above may occur concurrently or sequentially in one orseveral reactors. It is understood that best practice entails carefulmonitoring of reactant concentrations and of reaction products to adjustthe output ratios of hydrogen to carbon monoxide. It should be notedthat there is no catalyst involved as typical processes that rely onwater gas shift catalysts. The BMF char is a sacrificial agent for theultimate production of hydrocarbons, in essence representing a moreefficient use of the biomass. Temperature, pressure and space velocitywill affect the results and distribution of synthesis gas products. Thehydrogen to carbon monoxide ratio can be varied depending on the natureof feedstock and quantity of material. Indeed, a stream can beengineered to produce a stream comprising of 100% hydrogen, or one of100% carbon monoxide, or any compositional mixture of the two. Thus afeedstock comprised exclusively of methane can provide a source of purehydrogen, while a feedstock comprised of oxygen can provide a source ofpure carbon monoxide. The two sources can then be mixed in any ratio. AH₂/CO 2:1 ratio is preferable for the methanol production while dimethylether requires a 1:1 ratio.

Another method of adjusting ratio is to utilize a wider range ofreactants. A wide range of H2/CO ratios can be obtained from usingdifferent combinations of reactants, chosen from methane, oxygen, waterand carbon dioxide. The actual ratios will depend on the chemicalequilibrium of all species, which is determined by temperature,pressure, and concentration of reactants and products. As mentionedabove, energy for some of the BMF char reactions can be derived eitherfrom external or internal sources. External sources refer to energysupplied in the form of recycled waste heat, or waste heat orelectricity coming from outside the system described by the presentinvention. Internal sources refer to energy channeled from theexothermic reactions, such as shown in equations [4] and [5].

Thermal management via internal energy sources may be achieved with theappropriate combination of reactants to render the synthesis gasformation close to energy neutral.

Modifications may be made by those skilled in the art without affectingthe scope of the invention.

Although the invention is described above in terms of various exemplaryembodiments and implementations, it should be understood that thevarious features, aspects and functionality described in one or more ofthe individual embodiments are not limited in their applicability to theparticular embodiment with which they are described, but instead can beapplied, alone or in various combinations, to one or more of the otherembodiments of the invention, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like; the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof; the terms “a” or“an” should be read as meaning “at least one,” “one or more” or thelike; and adjectives such as “conventional,” “traditional,” “normal,”“standard,” “known” and terms of similar meaning should not be construedas limiting the item described to a given time period or to an itemavailable as of a given time, but instead should be read to encompassconventional, traditional, normal, or standard technologies that may beavailable or known now or at any time in the future. Likewise, wherethis document refers to technologies that would be apparent or known toone of ordinary skill in the art, such technologies encompass thoseapparent or known to the skilled artisan now or at any time in thefuture.

The presence of broadening words and phrases such as “one or more,” “atleast,” “but not limited to” or other like phrases in some instancesshall not be read to mean that the narrower case is intended or requiredin instances where such broadening phrases may be absent. Additionally,the various embodiments set forth herein are described in terms ofexemplary block diagrams, flow charts and other illustrations. As willbecome apparent to one of ordinary skill in the art after reading thisdocument, the illustrated embodiments and their various alternatives canbe implemented without confinement to the illustrated examples. Theseillustrations and their accompanying description should not be construedas mandating a particular architecture or configuration.

1. A method for producing synthesis gas from biomass, comprising: grinding a biomass feedstock to produce ground biomass particles; dispensing the ground biomass particles into thin sheets; subjecting the thin sheets of ground biomass to a treatment including sequential ramps of temperature followed by pressure shocks or pressure shocks concurrent with ramps of temperature; and recovering a residual non-volatile biomass component from the treatment and reacting the component with at least one of methane, oxygen, steam, and carbon dioxide, at high temperatures.
 2. The method of claim 1, wherein the biomass particles are ground to a diameter in the range of 0.001 inch to 1 inch, and wherein the thin sheets have a thickness that is a multiple of the ground biomass particle diameter.
 3. The method of claim 2, wherein the thickness of the thin sheets is between 1 and 30 times the biomass particle diameter.
 4. The method of claim 1, wherein the ramps of temperature vary from about 0.001° C./sec to about 1000° C./sec.
 5. The method of claim 4, wherein the ramps of temperature are varied over a period of time ranging from about 1 microsecond to about 1 week.
 6. The method of claim 1, wherein the pressure shocks are incremented over a range of pressures.
 7. The method of claim 1, wherein the pressure shocks are applied over a range of times varying from about 1 microsecond to about 1 week.
 8. The method of claim 1, wherein the pressure shocks vary in magnitude from about 0.2 MPa to about 10 GPa.
 9. The method of claim 8, wherein an admixture of pressure shocks of differing magnitudes are applied over a range of times.
 10. The method of claim 1, wherein the biomass is subjected to a controlled gas atmosphere or supercritical fluid while being subjected to a temperature ramp.
 11. The method of claim 1, in which the biomass is subjected to a controlled gas atmosphere or supercritical fluid while being subjected to pressure shocks.
 12. The method of claim 1, wherein the at least one collected gas component is selected from the group consisting of: lipids, furans, hydrocarbons or hydrocarbon fragments, and synthesis gas.
 13. The method of claim 1, wherein the temperature ramps include a sufficiently high temperature to create a non-volatile carbonaceous material from the biomass.
 14. The method of claim 13, wherein the temperature is above 300° C.
 15. The method of claim 1, wherein the pressure shocks increase thermal conductivity of formed non-volatile carbonaceous material within the biomass.
 16. The method of claim 1, wherein the non-volatile biomass component reacts sacrificially with methane.
 17. The method of claim 16, wherein the methane is derived from a wet gas source.
 18. The method of claim 1, wherein the reactant comprises oxygen and the oxygen is pure oxygen, part of a mixture of oxygen and an inert agent, or is derived from the decomposition of an oxygen-containing species, selected from the group consisting of: H₂O, H₂O₂, and N₂O.
 19. The method of claim 1, wherein the non-volatile component is activated prior to executing synthesis gas generation reactions.
 20. A method for adjusting the ratio of hydrogen to carbon monoxide in synthesis gas, comprising: grinding a biomass feedstock to produce ground biomass particles having diameters in the range of 0.001 inch to 1 inch; dispensing ground biomass into thin sheets having a thickness that is a multiple of the ground biomass particle diameter; subjecting the thin sheets of ground biomass to a treatment including sequential ramps of temperature followed by pressure shocks or pressure shocks concurrent with ramps of temperature; selectively collecting various groups of volatile compounds as they are released from the biomass; collecting a remaining non-volatile component of the thin sheets; reacting the non-volatile component with one of oxygen, methane, steam, and carbon dioxide; and adjusting a ratio of reacted oxygen, methane, steam, or carbon dioxide to produce synthesis gas having a hydrogen/carbon ratio in a range of 0 to
 100. 